Commissioning has begun on a pilot plant designed to demonstrate the effectiveness of a structured catalyst module for steam-methane reforming (SMR) that solves the main heat-transfer inefficiencies associated with the conventional process. The structured catalyst technology improves the efficiency of SMR and increases the hydrogen produced.
Steam reforming of methane — an endothermic reaction typically carried out in multi-tube, fixed-bed reactors filled with catalyst-laden ceramic pellets — is subject to heat-transfer inefficiencies due to the size and random placement of the pellets.
“Heat transfer in SMR reactors depends in large measure on feed gas impinging the boundary layer of fluid at the tube wall,” explains Bruce Boisture, president and co-founder of ZoneFlow Reactor Technologies, LLC (Windsor, Conn.; www.zoneflowtech.com), the developer of the new SMR technology. “But that heat-transfer mechanism is not optimized in the reactor tubes because of the random packing of the pellets in the reactor and their relatively large size (a concession to durability concerns) in relation to the diameter of the reactor tube. The result is a random gas-flow pattern within the reactor, sub-optimal heat transfer into the reactor and pressure drop across the reactor, and a significant amount of methane that can ‘bypass’ the catalyst along the tube walls. This high-temperature, but unreacted methane can cause coke buildup on the pellets.”
The ZoneFlow structured catalyst (photo) features precisely engineered flow channels in its outer casing that are designed to force the methane to contact the tube wall while minimizing pressure drop. The geometry of its support structure keeps the catalyst-coated casing in continuous contact with the tube wall despite tube creep, eliminating bypass, Boisture comments. “In testing, heat-transfer efficiency was improved by 100% while maintaining the same pressure drop,” Boisture says, which translates into an expected 15% higher throughput compared to conventional catalyst systems.
ZoneFlow’s pilot plant, located at the Université Catholique de Louvain (Belgium), is undergoing final commissioning now, and the plant will start up by the end of 2021. Pilot testing results are expected in mid-2022. In early November, ZoneFlow announced a joint development agreement with Honeywell UOP (Des Plaines, Ill.; www.uop.com) to develop and commercialize the technology. Honeywell says the ZoneFlow reactor technology allows capital savings for new SMR plants and higher productivity for existing plants, and the opportunity to reduce steam requirements for SMR will reduce energy demand and CO2 emissions.